#!/usr/bin/python
# -*- coding: utf-8 -*-

import socket
import thread
import time
import sys
import os
import httplib, urllib
import re

if __name__ == '__main__':
    try:
        i = raw_input()
        i = i.split()
        username = i[0]
        password = i[1]
        if username == password:
            print 'OK'
        else:
            print 'ERR'
    except KeyboardInterrupt:
        print "ERR"
        exit()
